What Your Patients Are Reading

Cardiology Review® Online, June 2012, Volume 28, Issue 3

Dark Chocolate’s Bright Side?

A new study has again brought attention to the potentially beneficial effects of dark chocolate on heart health (U.S. News & World Report, June 1, 2012). The British Medical Journal (online May 31, 2012) published a study by Ella Zomer and her colleagues at Monash University in Australia which suggests that daily consumption

of 100 grams of dark chocolate (at least 60% to 70% cocoa) may reduce the odds of heart attack and stroke in high-risk people.

The researchers said that 100% compliance with eating 100 grams/day of dark chocolate could potentially prevent 70 nonfatal and 15 fatal cardiovascular events per 10,000 people over 10 years; 80% compliance could prevent 55 nonfatal and 10 fatal cardiovascular events. The study also concluded that promoting the daily consumption of dark chocolate at a cost of $42 per person per year would be a cost-effective strategy for reducing cardiovascular events in high-risk people.

Several earlier studies have also shown a positive cardiovascular effect to be associated with dark chocolate, likely because dark chocolate is rich in antioxidant flavonoids. The Australian study was based on a mathematical model used to predict the long-term health effects of daily consumption of dark chocolate among over 2000 people with hypertension and metabolic syndrome (but without a history of heart disease or diabetes, and not taking antihypertensive medications). There were mixed reviews of the findings because they are based on a mathematical model that is hypothetical, and because there are concerns that consuming dark chocolate—and its additional sugar and calories—could have unintended adverse consequences.

Well, LDL Is Still Bad for You…

High levels of high-density lipoprotein (HDL) cholesterol—commonly called “good” cholesterol to distinguish it from its evil relative, low-density lipoprotein (LDL)

cholesterol—have long been thought to boost cardiovascular health. Now a study published online in The Lancet has challenged that tenet (Yahoo! News, May 17, 2012).

Investigators found no evidence that higher levels of HDL cholesterol routinely reduce the risk of heart attack. Led by Dr Sekar Kathiresan, director of preventive cardiology at Massachusetts General Hospital and a geneticist at the Broad Institute of MIT and Harvard, the team used Mendelian randomization to compare heart attack risk among people who inherited known genetic variants that gave them high HDL levels. These individuals should have a lower risk of heart attack, but in fact the study found this was not always the case.

“These results show that some ways of raising HDL cholesterol might not reduce risk of myocardial infarction in human beings,” said Dr Kathiresan. “Therefore, if an intervention such as a drug raises HDL cholesterol, we cannot automatically assume that risk of myocardial infarction will be reduced.” The study did find that LDL levels remained an accurate marker of cardiac risk.